Numerical Characterization Of The "Black Hole" Effect And Design Method Of Light Environment For Awning Of Highway Tunnel Entrance

The "black hole" effect at the entrance of highway tunnels in the daytime has greatly aggravated the driver's life and psychological burden,and the high accident risk caused by it has long troubled the public's safe travel.At present,there are fewer awnings at the entrance of highway tunnels,which have many types,different lengths and large experience design components,It is difficult to support the scientific design of its decreasing light environment by existing research.Carrying out the numerical characterization of the "black hole" effect of the tunnel entrance,and then proposing the light environment design method of the awning,which is of great significance for reducing or even eliminating the "black hole" effect of the tunnel entrance on the serious impact of traffic safety.Based on the driver's direct perception index of light and shade in tunnel entrance "black hole" effect—viewpoint illumination,this paper carries out a real vehicle test on the driver's perception of "black hole" effect at tunnel entrance of highway in different areas,the illuminometer is used to measure the driver's viewpoint illumination change and record his visual perception degree when he passes through tunnel entrance,and different visual perception classification results is obtained according to the adjacent ratio model,the grading threshold of driver's visual perception is obtained by using the fuzzy K-means algorithm,which reveals the essential connotation of driver's light and shade perception grading and illumination change.Based on optimized Ecotect Analysis light environment simulation technology,the awning and its connected tunnel model are constructed,and the illumination of 4/6 lane tunnel entrance under different illumination levels and control speeds is analyzed,and the setting conditions of tunnel entrance awning are proposed.The initial length of the awning is determined by combining the minimum theoretical length of two times with the maximum sectional length.The numerical simulation of the illumination at the viewpoint position in the whole length of the awning with different combination of the transmission parameters of the awning material under the length is carried out,based on the illuminance change index of the driver's visual comfort,the reasonable length of the awning and the light-transparent parameter combination scheme of the awning material under different viewpoint illumination levels and control speeds are obtained,and the design method of the decreasing light environment of the "single section and integral combination" type awning is put forward.Taking the entrance of 4/6 lane highway tunnel as the object of study,the combination of the length of awning and the transmittance parameters of awning material are determined by reference method and light environment simulation method respectively.The research results can provide a scientific theoretical basis and method support for the setting of light-reducing structures at the entrance of highway tunnel,it is helpful to eliminate the "black hole" effect of tunnel entrance fundamentally and is expected to realize the safety of highway tunnel operation..